Notched finned heat sink structure

ABSTRACT

A heat sink structure having a pipe attached to a plurality of fins for dissipating heat into an environment. Each fin in the plurality is constructed of a thermally conductive material and has a cavity formed therein dimensioned for seating about the pipe exterior surface. An opening or notch extends from the edge of each of the fins to the cavity to facilitate the spread of an adhesive or solder to the fin/pipe interface for providing thermal and physical coupling of the plurality of fins to the pipe.

FIELD OF THE INVENTION

[0001] This invention relates to heat sinks and methods of making thesame.

BACKGROUND OF THE INVENTION

[0002] Known finned heat sink structures include a plurality of closelydisposed heat dissipating fins that are joined to a heat pipe or fluidtransfer tube by use of a thermally conductive adhesive or solder. Eachof the fins has a cavity about its center region dimensioned toaccommodate the heat pipe or fluid transfer tube. Because of the closeproximity of the fins to each other when mated with the pipe, it isdifficult to apply the adhesive or solder near the interface of the fincavity and the heat pipe so as to efficiently assemble the finned heatsink structure. Accordingly, an improved heat sink structure is desiredwhich allows solder to be easily applied to a heat pipe mated with aplurality of fins.

SUMMARY OF THE INVENTION

[0003] The present invention is directed to a heat sink structure havinga heat conduit such as a pipe, connected to a plurality of fins. Thefins dissipate heat into an environment containing the heat sinkstructure. Each fin in the plurality is constructed of a thermallyconductive material having two opposing faces and an edge. The opposingfaces define a cavity therein which is dimensioned for seating about thepipe exterior surface. The edge defines an opening having a sidewallextending from the edge to the cavity. Means are provided for attachingthe plurality of fins to the exterior surface of the pipe. For example,solder or adhesive is applied to the pipe via access through theopening.

[0004] The present invention is also directed to a method of making aheat sink structure. The inventive method includes providing a pluralityof fins, with each fin being constructed of a thermally conductivematerial having two opposing faces and an edge. The opposing facesdefine a cavity therein which is partially bounded by a flange. The edgedefines an opening extending from the edge to the cavity. A pipe is thendisposed within the cavity of each fin so that the pipe outer surfacerests on a portion of each said flange. An adhesive material is disposedon the pipe outer surface by accessing the pipe outer surface throughthe openings in the fins.

[0005] Other objects and features of the present invention will becomeapparent from the following detailed description considered inconjunction with the accompanying drawings. It is to be understood,however, that the drawings are designed solely for purposes ofillustration and not as a definition of the limits of the invention, forwhich reference should be made to the appended claims. It should befurther understood that the drawings are not necessarily drawn to scaleand that, unless otherwise indicated, they are merely intended toconceptually illustrate the structures and procedures described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] In the drawings:

[0007]FIG. 1 depicts a plurality of fins attached to a heat pipe inaccordance with the present invention; and

[0008]FIG. 2 depicts a detail of one of the fins of the device in FIG.1.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

[0009] A heat sink structure 10 in accordance with a preferredembodiment of the present invention is depicted in FIG. 1. The heat sinkstructure includes a pipe 12 connected at one end to a plurality of fins14, with the other end of the pipe connected to a heat source 16 such asan evaporator block containing or supporting an integrated circuit, etc.The pipe 12 provides a conduit for heat exchange between the source 16and the fins 14 to allow for heat carried by the pipe 12 to the fins tobe dissipated to the environment, in a manner well known to those havingordinary skill in the art. The pipe 12 may be a solid heat pipe or afluid transfer tube containing fluid for providing the desired heatexchange between the source 16 and the fins 14.

[0010] With reference to FIG. 2, each fin 14 is preferably constructedof a thermally conductive sheet or plate material having a front face 16and a rear face 18 and defining a cavity 20 formed therein. The cavity20 is preferably dimensioned for seating about a diameter of the pipe 12as discussed more fully below. Thus, for a pipe having a circular crosssection of a particular diameter, the cavity 20 is dimensioned slightlylarger than the pipe diameter. The cavity 20 is bounded by a sidewall oredge 22 at which a flange 24 is preferably attached for providing aninterface between the pipe and the fins 14. Thus, when the pipe 12 isinserted into or otherwise disposed within the cavities 20, the flange24 collars or substantially surrounds a circumference of the pipe, asshown in FIG. 1. The flange 24 also provides an offset or space betweenadjacent fins in the plurality as shown in FIG. 1. Although the flange24 is depicted in FIG. 2 as depending from one face of the fin (e.g.,face 16) it will be readily recogized that the flange may extend fromeither or both faces without departing from the scope of the invention.

[0011] It should be appreciated that for fins 14 having specificthicknesses, the edge or sidewall 22 may provide adequate contact withthe pipe surface, in which event the flange 24 may not be required.

[0012] With continued reference to FIG. 2, each fin 14 has an edge 26defining and opening 28 extending from the edge 26 to the cavity 20. Theopening has a pair of walls or edges 30 which are preferably taperedinwardly toward each other (as shown) so that the opening 28 resembles a‘V’-shaped notch. Alternatively, the opening may be configured as a‘U’-shape or semi-circular shape so long as it provides its intendedpurpose of facilitating application of solder material to the pipe andfins in a manner described below.

[0013] When pipe 12 is in place in the cavities 20, it must be thermallycoupled and adhered to the fins 14 to provide for heat conduction. Thisis accomplished by applying a thermally conductive adhesive or bondingagent such as a solder material 32 for joining the pipe to the fins.Specifically, openings 28 provide access to an exposed region of thepipe surface area for disposing the solder 32 either directly thereon,or by applying solder to the opening sides 30 and heating the heat sinkstructure to cause the solder to flow downward along the sides 30 to thepipe 10. Thus, the opening 28 in the fin allows for ease of applicationof the solder to the fin and pipe interface area, i.e. to the area wherethe flange 24 meets the heat pipe 10.

[0014] An efficient thermal contact results when the solder or bondingmaterial 32 flows and adheres between the flange 24 and all orsubstantially all of the contact area between the pipe and the flange orwall 22 so that air bubbles that may be present in the contact area areremoved. This is facilitated by providing an additional opening or notch36 located at the cavity and flange interface which allows theattachment solder or epoxy to wick or flow along the surface of the pipeand along the flange so that, when cured, the solder will bond andprovide thermal coupling between the pipe and fins.

[0015] The application of the solder 32 can be in a preform or pastethat is applied to the sidewalls 30, either before or after the pipe isdisposed in the cavities 20, or may be disposed directly in the opening28 once the pipe is in place.

[0016] To assemble the components of the inventive heat sink 10, thefins 14 can be placed on the pipe 12 in any known manner. For example,they can be placed over a free end of the pipe one at a time by simplyaligning and mating the pipe with the cavity of each fin. Alternatively,the fins can be pre-stacked or aligned in a support structure (notshown) whereupon the end of the pipe can be fed through the fin cavitiessimultaneously. In a further alternate embodiment, rather than feedingthe end of the pipe through the cavities, a length of the pipe may belaid within the opening 28 and forced downward into the cavities 20 byapplying a downward force in a direction of arrow X. As a result of thetapered sides 30, this will cause the sides to temporarily separate in adirection shown by arrows Y to allow passage of the pipe into thecavity, whereupon the sides will spring back to their rest position(shown in FIG. 1). In either case, once the pipe is in place, the solderor adhesive will be cured between the fins and the pipe, such as byheating the heat sink structure to allow a preform to flow or byapplying a paste or preform and then heating the structure.

[0017] Thus, while there have shown and described and pointed outfundamental novel features of the invention as applied to a preferredembodiment thereof, it will be understood that various omissions andsubstitutions and changes in the form and details of the devicesillustrated, and in their operation, may be made by those skilled in theart without departing from the spirit of the invention. For example, itis expressly intended that all combinations of those elements and/ormethod steps which perform substantially the same function insubstantially the same way to achieve the same results are within thescope of the invention. Moreover, it should be recognized thatstructures and/or elements and/or method steps shown and/or described inconnection with any disclosed form or embodiment of the invention may beincorporated in any other disclosed or described or suggested form orembodiment as a general matter of design choice. It is the intention,therefore, to be limited only as indicated by the scope of the claimsappended hereto.

What is claimed is:
 1. A heat sink structure, comprising: a pipe having an exterior surface; a plurality of fins to dissipate heat into an environment containing the heat sink structure, each fin in the plurality being constructed of a thermally conductive material and having two opposing faces and an edge, the opposing faces defining a cavity therein dimensioned for seating about the pipe exterior surface, said edge defining an opening having a sidewall extending from the edge to the cavity; and means for attaching the plurality of fins to the exterior surface of the pipe.
 2. The heat sink structure of claim 1, wherein the pipe is one of a heat pipe and a fluid transfer tube.
 3. The heat sink structure of claim 1, wherein at least one fin in the plurality comprises a flange positioned about a periphery of the cavity for attaching the at least one fin to the exterior surface of the pipe.
 4. The heat sink structure of claim 1, wherein the opening of each of the fins are aligned to form a single channel.
 5. The heat sink structure of claim 1, wherein the opening sidewall comprises a pair of opposing sidewalls tapered inwardly from the edge to the cavity.
 6. The heat sink structure of claim 3, wherein the flange has opposing edges about the opening.
 7. The heat sink structure of claim 1, wherein the attaching means comprises a solder preform.
 8. The heat sink structure of claim 1, wherein the attaching means comprises a solder paste.
 9. The heat sink structure of claim 6, wherein said opposing edges are tapered relative to a plane containing the at least one fin.
 10. A method of making a heat sink structure, comprising the steps of: providing a plurality of fins, each fin being constructed of a thermally conductive material having two opposing faces and an edge, the opposing faces defining a cavity therein which is partially bounded by a flange, the edge defining an opening extending from the edge to the cavity; disposing a pipe within the cavity of each fin so that the pipe outer surface rests on a portion of each said flange; and disposing an adhesive material on said pipe outer surface by accessing the pipe outer surface through the openings in the fins.
 11. The method of claim 10, wherein the pipe is one of a heat pipe and a fluid transfer tube.
 12. The method of claim 10, wherein said disposing step comprises feeding the pip through the fin cavities.
 13. The method of claim 10, wherein said disposing step comprises placing the pipe of the openings of the plurality of fins and applying a force so that the pipe moves within the cavities.
 14. The method of claim 10, wherein the opening comprises a ‘V’-shaped opening.
 15. The method of claim 10, wherein said adhesive comprises a solder material. 